BGB203 AT command set problem

Hi, i m doing a project with the DIP BGB203 bluetooth module.

I use a USB to TTL serial cable(3.3V) as interface, i can detect the module with my mobile phone or my laptop but impossible to communicate with the AT command set, i don’t receive data.

I checked on the forum it seems to be a problem, i changed the baud rate, checked the different voltages… I don’t know how to use the command mode…Is anybody know how to do it?